MERGE INTO：存在就更新不存在就新增——oracle

MERGE INTO [your table-name] [rename your table here]

USING ( [write your query here] )[rename your query-sql and using just like a table]

ON ([conditional expression here] AND [...]...)

WHEN MATCHED THEN [here you can execute some update sql or something else ]

WHEN NOT MATCHED THEN [execute something else here ! ]

 

做用:判斷Ｂ表和Ａ表是否知足ON中條件，若是知足則執行知足後面的update SQL，若是不知足，則執行不知足後面的insert SQL。

例子：

使用狀況，例如：若是數據庫中存在數據就update，若是不存在就insert。

MERGE INTO  TEST T1

USING (SELECT '2' as ID, 'newtest2' as NAME FROM dual) T2 on (T1.ID=T2.ID)

WHEN MATCHED THEN UPDATE SET T1.NAME=T2.NAME

WHEN NOT MATCHED THEN  INSERT (T1.ID, T1.NAME) VALUES (T2.ID, T2.NAME );